U.S. patent application number 11/501375 was filed with the patent office on 2007-03-22 for stabilizing griess reagent for explosives detection.
This patent application is currently assigned to The Regents of the University of California. Invention is credited to M. Leslie Carman, Adam H. Love, Peter J. Nunes, John G. Reynolds.
Application Number | 20070065944 11/501375 |
Document ID | / |
Family ID | 37884690 |
Filed Date | 2007-03-22 |
United States Patent
Application |
20070065944 |
Kind Code |
A1 |
Nunes; Peter J. ; et
al. |
March 22, 2007 |
Stabilizing Griess reagent for explosives detection
Abstract
The present invention provides a system wherein the Griess
reagent has the ambient atmosphere removed. The present invention
provides a system to treat the Griess reagent to improve storage
lifetimes at room temperature or higher to over a year or more. The
present invention greatly extends the useful lifetime of
preparations of the Griess reagent as well as broadens the
applications to field testing equipment.
Inventors: |
Nunes; Peter J.; (Danville,
CA) ; Love; Adam H.; (Berkeley, CA) ; Carman;
M. Leslie; (San Ramon, CA) ; Reynolds; John G.;
(San Ramon, CA) |
Correspondence
Address: |
Eddie E. Scott;Assistant Laboratory Counsel
Lawrence Livermore National Laboratory
P.O. Box 808, L-703
Livermore
CA
94551
US
|
Assignee: |
The Regents of the University of
California
|
Family ID: |
37884690 |
Appl. No.: |
11/501375 |
Filed: |
August 8, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60706911 |
Aug 9, 2005 |
|
|
|
Current U.S.
Class: |
436/8 |
Current CPC
Class: |
Y10T 436/10 20150115;
G01N 31/224 20130101 |
Class at
Publication: |
436/008 |
International
Class: |
G01N 31/00 20060101
G01N031/00 |
Goverment Interests
[0002] The United States Government has rights in this invention
pursuant to Contract No. W-7405-ENG-48 between the United States
Department of Energy and the University of California for the
operation of Lawrence Livermore National Laboratory.
Claims
1. A method for stabilizing Griess reagent, comprising the steps
of: providing the Griess reagent, and stabilizing the Griess
reagent.
2. The method for stabilizing Griess reagent of claim 1 wherein
said step of stabilizing the Griess reagent comprises stabilizing
the Griess reagent by removing ambient atmosphere.
3. The method for stabilizing Griess reagent of claim 1 wherein
said step of stabilizing the Griess reagent comprises removing
ambient atmosphere with a vacuum.
4. The method for stabilizing Griess reagent of claim 1 wherein
said step of stabilizing the Griess reagent comprises removing
ambient atmosphere with an inert gas.
5. A method for stabilizing Griess reagent, comprising the steps
of: providing the Griess reagent, and stabilizing the Griess
reagent by removing ambient atmosphere.
6. The method for stabilizing Griess reagent of claim 5 wherein
said step of stabilizing the Griess reagent by removing ambient
atmosphere comprises freezing the Griess reagent and removing
ambient atmosphere with a vacuum.
7. A method for stabilizing Griess reagent, comprising the steps
of: providing the Griess reagent, and stabilizing the Griess
reagent by removing ambient atmosphere, wherein said step of
stabilizing the Griess reagent by removing ambient atmosphere
comprises removing ambient atmosphere with an inert gas.
8. The method for stabilizing Griess reagent of claim 7 wherein
said step of removing ambient atmosphere with an inert gas
comprises removing ambient atmosphere with a purified inert
gas.
9. The method for stabilizing Griess reagent of claim 7 wherein
said step of removing ambient atmosphere with an inert gas
comprises removing ambient atmosphere with nitrogen.
10. The method for stabilizing Griess reagent of claim 7 wherein
said step of removing ambient atmosphere with an inert gas
comprises removing ambient atmosphere with argon.
11. The method for stabilizing Griess reagent of claim 7 wherein
said step of removing ambient atmosphere with an inert gas
comprises removing ambient atmosphere with helium.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 60/706,911 filed Aug. 9, 2005 and titled
"Stabilizing Griess Reagent for Explosives Detection." U.S.
Provisional Patent Application No. 60/60/706,911 filed Aug. 9, 2005
and titled "Stabilizing Griess Reagent for Explosives Detection" is
incorporated herein by this reference.
BACKGROUND
[0003] 1. Field of Endeavor
[0004] The present invention relates to detecting explosives and
more particularly to a stabilizing Griess reagent for explosives
detection.
[0005] 2. State of Technology
[0006] U.S. Pat. No. 5,638,166 for an apparatus and method for
detection of explosives issued Jun. 10, 1997 to Herbert Funsten and
David McComas provides the following state of the art information:
"Explosives are a core component of nuclear, biological, chemical
and conventional weapons, as well as of terrorist devices such as
car, luggage, and letter bombs. Current methods for detecting the
presence of explosives include vapor detection, bulk detection, and
tagging . . . . It is known that surfaces in contact with
explosives (for example, during storage, handling, or device
fabrication) will readily become contaminated with explosive
particulates as a result of their inherent stickiness . . . .
Furthermore, cross contamination in which a secondary surface is
contaminated by contact with a contaminated primary surface can
also readily occur . . . . Therefore, explosive residue will likely
persist in large amounts on the explosive packaging and environs,
as well as on the individuals involved in building the explosive
device, which can provide an avenue for detection of the presence
of explosives."
[0007] U.S. Pat. No. 5,679,584 for a method for chemical detection
issued Oct. 2, 1997 to Daryl Sunny Mileaf and Noe Esau Rodriquez,
II provides the following state of the art information: "a method
for detecting a target substance which includes collecting a
substance sample; introducing the substance sample into a substance
card having at least one preselected reagent responsive to the
presence of the target substance and having a light-transmissive
chamber; and inserting the substance card into a substance detector
device having a photosensor and adapted to receive the substance
card. Once the substance detector card has been inserted into the
substance detector, the method continues by mixing the substance
sample with the preselected reagents for a preselected mixing
period, thus producing a measurand having a target substance
reaction."
[0008] U.S. Pat. No. 6,470,730 for a dry transfer method for the
preparation of explosives test samples issued Oct. 29, 2002 to
Robert Chamberlain provides the following state of the art
information: ". . . method of preparing samples for testing
explosive and drug detectors of the type that search for particles
in air. A liquid containing the substance of interest is placed on
a flexible Teflon.RTM. surface and allowed to dry, then the
Teflon.RTM. surface is rubbed onto an item that is to be tested for
the presence of the substance of interest. The particles of the
substance of interest are transferred to the item but are readily
picked up by an air stream or other sampling device and carried
into the detector."
SUMMARY
[0009] Features and advantages of the present invention will become
apparent from the following description. Applicants are providing
this description, which includes drawings and examples of specific
embodiments, to give a broad representation of the invention.
Various changes and modifications within the spirit and scope of
the invention will become apparent to those skilled in the art from
this description and by practice of the invention. The scope of the
invention is not intended to be limited to the particular forms
disclosed and the invention covers all modifications, equivalents,
and alternatives falling within the spirit and scope of the
invention as defined by the claims.
[0010] The Griess reagent is used in colormetric detection of
nitrogen-oxide species. Whether the source of the nitrogen are
biological systems (such as cell function), or in chemical systems
(such as high explosives), the Griess reagent reacts with nitrogen
oxides to produce a highly colored azo-dye which is used as a
simple indicator. Although widely used in many commercial and
research applications, the Griess reagent has only limited storage
lifetime, typically 1 to 4 months, due to decomposition which
produce colored impurities, rendering it unusable for detection.
The present invention provides a method in which to treat the
Griess reagent to improve storage lifetimes at room temperature or
higher to over a year or more. This method greatly extends the
useful lifetime of preparations of the Griess reagent as well as
broadens the applications to field testing equipment.
[0011] The present invention provides a method for stabilizing
Griess reagent comprising the steps of providing the Griess
reagent, and stabilizing the Griess reagent. In one embodiment, the
present invention provides a method for stabilizing Griess reagent
comprising the steps of providing the Griess reagent and
stabilizing the Griess reagent by removing ambient atmosphere. In
another embodiment, the present invention provides a method for
stabilizing Griess reagent comprising the steps of providing the
Griess reagent and stabilizing the Griess reagent by removing
ambient atmosphere wherein the step of stabilizing the Griess
reagent by removing ambient atmosphere comprises removing ambient
atmosphere with an inert gas.
[0012] The present invention has use as a stand alone rapid test
for explosives to be used by field and laboratory personnel to
determine the presence and types of explosives. The present
invention is of interest to the US Military, EPA, Law enforcement,
and other civilian agencies needing explosives identification and
forensic analysis. Long storage lifetimes are necessary. In private
industry the present invention has uses in an explosives detection
kit. Also, many companies sell Griess reagent kits for biochemical
applications. Long storage lifetimes would greatly increase the
commercial value.
[0013] The invention is susceptible to modifications and
alternative forms. Specific embodiments are shown by way of
example. It is to be understood that the invention is not limited
to the particular forms disclosed. The invention covers all
modifications, equivalents, and alternatives falling within the
spirit and scope of the invention as defined by the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The accompanying drawings, which are incorporated into and
constitute a part of the specification, illustrate specific
embodiments of the invention and, together with the general
description of the invention given above, and the detailed
description of the specific embodiments, serve to explain the
principles of the invention.
[0015] FIG. 1A shows a bottle containing a freshly prepared Griess
reagent.
[0016] FIG. 1B shows a bottle containing the same Griess reagent
stored in tightly sealed closed containers at room temperature
after 30 days.
[0017] FIG. 2 is a graph that shows UV-visible spectrum of vacuum
sealed Griess reagent ampoules at room temperature and at
60.degree. C.
[0018] FIG. 3 shows one of the samples after 230 days.
[0019] FIG. 4 illustrates an inspection tester for explosives
utilizing the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0020] Referring to the drawings, to the following detailed
description, and to incorporated materials, detailed information
about the invention is provided including the description of
specific embodiments. The detailed description serves to explain
the principles of the invention. The invention is susceptible to
modifications and alternative forms. The invention is not limited
to the particular forms disclosed. The invention covers all
modifications, equivalents, and alternatives falling within the
spirit and scope of the invention as defined by the claims.
[0021] The ability to identify unknown explosives in the field is
of utmost importance to the military, law enforcement and Homeland
Security forces worldwide. Spot tests for the identification of
explosives have been used in combination with thin-layer
chromatography and in forensic analysis. There are some commercial
companies (Mistral, Securesearch, Duram products) who have produced
explosives identification kits similar to LLNL technology. They
have incorporated similar color reagents and have been used by the
military and law-enforcement agencies. They allow the
identification of nitroaromatics, nitramines, ammonium nitrate, and
recently the potassium chlorate-based explosives. Their systems are
available as spray kits or solution-drop kits.
[0022] Key to the explosive testing technology described above is
the Griess reagent. Known since 1879, the Griess reagent reacts
with nitrogen oxide compounds, whether bound or free, and produces
a highly colored compound that can be used for visible detection.
This colored compound has been shown to be an effective indicator
for not only high explosives, but other source of nitrogen oxides,
such as biological systems.
[0023] Although known and used commercially and in research for
over a century, the Griess reagent exhibits an intrinsic
instability that has not ever been fully addressed. This
instability lessens the effectiveness of the use of the Griess
reagent due to reducing its storage life significantly.
[0024] This instability is demonstrated in FIGS. 1A and 1B. FIG. 1A
shows a bottle containing a freshly prepared Griess reagent. As
illustrated in FIG. 1A, the solution is colorless. FIG. 1B shows a
bottle containing the same Griess reagent stored in tightly sealed
closed containers at room temperature after 30 days. The FIG. 1B
sample is visibly colored. This color is sufficient enough and
covers the visible spectrum in such a way that it will interfere
with precise indication of the presence of nitrogen oxides.
Similarly, if the reagent is stored where the container is not
tightly sealed, the interfering color becomes highly intense in the
same amount of time, making the reagent completely unusable.
[0025] The amount of colored compound formed depends upon the
method of sealing the container, and the temperature of storage.
Under normal storage conditions, no matter how carefully the
preparation is done, the Griess reagent will produce this color.
Commercial producers of the reagent recognize the instability. A
typical instruction (taken for the product catalog of a vendor) on
handling the Griess reagent are as follows: Store at 4.degree. C.;
keep all solutions in their original light-protective plastic
bottles; return to refrigerator as soon as possible; storage
lifetime is about 4 months.
[0026] The present invention provides a set of simple methods that
will stabilize the Griess reagent towards the formation of the
colored interfering compounds shown. to be formed in normal and
commercial preparations of the Griess reagent. In all preparations,
the Griess reagent is prepared by the method of J. B. Fox
(Analytical Chemistry, 51(9), 1493 (1979)). This is not meant to
limit the method of synthesis, just to give an example. Other
published methods are just as adequate. The example of the method
of stabilizing the reagent is also shown as an example and is not
meant to limit the methods of stabilization.
[0027] A 2-gram solution of Griess reagent was placed in a 5 mL
glass ampoule. The ampoule was then connected to a vacuum line. The
ampoule was then frozen in liquid nitrogen. When the solution was
completely frozen, the system was pumped out until no gas evolved
further. The ampoule was then isolated from the vacuum system. The
ampoule was let to thaw to room temperature. The whole process was
repeated two more times. After pumping down the third time, the
neck of the ampoule was sealed with a torch and the ampoule was
then thawed. Several ampoules were prepared this way. Some were
left at room temperature and some were placed in a constant heating
bath at 60.degree. C. to accelerate the formation of the colored
interference. (An accelerated aging method has been developed to
reduce the evaluation time from months to one day.) After 6 months,
all the ampoules that were properly sealed exhibited no evidence of
the formation of the colored interference.
[0028] FIG. 2 shows one example this study. In this study, the
ampoules are still colorless after 300 days and are currently still
being studied. FIG. 2 is a graph that shows UV-visible spectrum of
vacuum sealed Griess reagent ampoules at room temperature and at
60.degree. C. Data extends to at least 300 days as on 5.8.05 and is
currently being monitored.
[0029] FIG. 3 shows a photograph of one of the samples after 230
days. The color impurity is monitored at 500 nm by a UV-vis
spectrometer. In addition, all samples that were not correctly
sealed very quickly exhibited dark color within 24 hours in the
accelerated aging study. Clearly, the Griess reagent preparation
that includes the vacuum treatment step produces a stabilized
Griess reagent that does not produce the colored interference.
[0030] The above is just one method of stabilizing the Griess
reagent. This example was used to develop analysis protocols.
Several other methods of stabilization are just as effective and
are preferred because of ease of application. Preferred methods are
purging the bulk preparation of the Griess reagent with purified
inert gases such as nitrogen, argon, helium. In these methods, 100
grams of Griess reagent are prepared by literature methods. The
whole batch is then placed into a flask that can be isolated from
ambient air, preferably with a serum stopper, and pure nitrogen is
bubbled through the system. The length of time for bubbling
depended upon the ambient conditions under which the Griess reagent
is prepared. Once the bulk reagent was purged, samples were
transferred by cannula to smaller vials and these vials were
analyzed in the accelerated aging test. No sample has yet to show
the colored interference after one month at 60.degree. C. This
translates to storage lifetimes of well over one year at room
temperature.
[0031] Referring now to FIG. 4, an embodiment of the present
invention is illustrated in connection with an inspection tester
for explosives. This embodiment of the present invention is
designated generally by the reference numeral 400. The inspection
tester 400 is an all-inclusive, inexpensive, and disposable device.
The inspection tester can be used anywhere as a primary screening
tool by non-technical personnel to determine whether a surface
contains explosives. The inspection tester 400 was developed to
allow identification of explosives. This inspection tester may be
used by first responders, military, law enforcement and Homeland
Security.
[0032] The inspection tester 400 provides a small, disposable,
one-use system. The inspection tester 400 uses a simple and rapid
method of operation. A removable swab unit sample pad 401 is
exposed to a suspect substance. This may be accomplished by the
swab unit sample pad 401 being swiped across a surface containing
the suspect substance or the swab unit pad 401 may be exposed to
the suspect substance in other ways such as adding the suspect
substance to the swab unit sample pad 401.
[0033] The inspection tester 400 comprises an explosives tester
body 402 and the removable swab unit 401 adapted to be removably
positioned in the explosives tester body 402. The removable swab
unit 401 includes a lateral flow membrane 411, an area 412 so that
the swab unit can be easily inserted and removed from the
explosives tester body 402. The removable swab unit 401 also
includes an information area 413 and color reaction indicators
414.
[0034] The explosives tester body 402 includes a printable backing
card 403 that adds stiffness and infographics. A heat seal pattern
404 adds strength to avoid warping. A section 405 of the explosives
tester body 402 provides an area for printed graphics and thumb
placement and step numbering. The explosives tester body 402
includes a beveled docking entry portion 406 and a tab 407 for easy
docking of the removable swab unit sample pad 401.
[0035] The explosives tester body 402 includes Meisenheimer
Complexes ampoule 408 and Griess Reagent ampoule 409. In various
embodiments, Meisenheimer Complexes ampoule 408 and Griess Reagent
ampoule 409 are breakable ampoules, breakable glass ampoules,
squeezable ampoules, and other types of ampoules. As shown in FIG.
4, Meisenheimer Complexes ampoule 408 includes indentations 410 on
the chamber which keeps glass pieces from adhering to the
walls.
[0036] The lateral flow membrane 411 makes up the bulk of the
removable swab unit 401. The lateral flow membrane 411 comprises a
microporous membrane that provides migration of fluids from
Meisenheimer Complexes ampoule 408 and fluids from Griess Reagent
ampoule 409. Lateral flow membranes are known for their use in
other fields such as blotting techniques, enzyme-linked
immunosorbent assay (ELISA) testing, and lateral-flow
immunochromatographic tests. The lateral flow membrane 411 is a
Porex Lateral-Flo Membrane. The lateral flow membrane 411 comprises
polyethylene spheres fused into a Lateral-Flo.TM. membrane.
Applicants experimentally determined that the properties of Porex
make it an ideal swipe material for the inspection tester 400. The
lateral flow membrane 411 is chemical resistant, withstands heat as
high as 430.degree. C., is durable, is inexpensive, can be cut to
any size, and concentrates suspect materials along the solvent
front making calorimetric detection limits. The lateral flow
membrane 411 provides a high surface area swipe for sample
collection.
[0037] Meisenheimer Complexes ampoule 408 and Griess Reagent
ampoule 409 provide two reagent activation units. Meisenheimer
Complexes ampoule 408 (for reagent A) and Griess Reagent ampoule
409 (for reagent B) are operatively mounted on the explosives
tester body 402. The Meisenheimer Complexes ampoule 408 containing
the first explosives detecting reagent A is positioned to deliver
the first explosives detecting reagent A to the lateral flow
membrane 411. The Griess Reagent ampoule 409 containing the second
explosives detecting reagent B is positioned to deliver the second
explosives detecting reagent B to the lateral flow membrane 411.
The reagent A contains Meisenheimer Complexes ampoule. The reagent
B provides a Griess reaction. The present invention provides a
system wherein the Griess reagent is connected to a vacuum in
preparation. The present invention provides a system to treat the
Griess reagent to improve storage lifetimes at room temperature or
higher to over a year or more. The present invention greatly
extends the useful lifetime of preparations of the Griess reagent
as well as broadens the applications to field testing
equipment.
[0038] The inspection tester 400 uses a simple and rapid procedure
summarized by the following four step operation:
[0039] STEP 1) A suspect surface is swiped with the removable swab
unit sample pad 401. This may be accomplished by the swab unit
sample pad 401 being swiped across a surface containing the suspect
substance or the swab unit pad 401 may be exposed to the suspect
substance in other ways such as adding the suspect substance to the
swab unit sample pad 401. This will cause any explosives residue to
be collected and held by the swab unit sample pad 401.
[0040] STEP 2) The breakable or squeezable Meisenheimer Complexes
ampoule 408 is located in a position to deliver the first
explosives detecting reagent A to the lateral flow membrane 411.
The breakable or squeezable Meisenheimer Complexes ampoule 408 is
pressed to break or squeeze it thereby dispensing reagent A onto
the lateral flow membrane 411. The regent A contacts any explosives
residue that has been collected by the swab unit sample pad 401.
The lateral flow membrane 411 concentrates suspect materials along
the solvent front. If the swab unit sample pad 401 becomes colored,
the test is positive for explosives. If no color appears, the test
for explosives is negative to this point.
[0041] STEP 3) If STEP 2 is negative to this point, the inspection
tester 400 is positioned in the portable heating unit 300. The
heating unit 300 is activated. This causes the swab unit sample pad
401, reagent A, and any explosives residue to become heated. If the
swab unit sample pad 401 now becomes colored, the test is positive
for explosives. If no color appears, the test for explosives is
negative to this point.
[0042] STEP 4) The breakable or squeezable Griess Reagent ampoule
409 is located in a position to deliver the second explosives
detecting reagent B to the lateral flow membrane 411. If STEP 3 is
negative to this point, the breakable or squeezable Griess Reagent
ampoule 409 is pressed to brake or squeeze it thereby dispensing
reagent B onto the lateral flow membrane 411. The regent B contacts
any explosives residue that has been collected by the swab unit
sample pad 401., The lateral flow membrane 411 concentrates suspect
materials along the solvent front. If the swab unit sample pad 401
becomes colored, the test is positive for explosives. If no color
appears, the test for explosives is negative.
[0043] In the embodiment of the present invention 400, the Griess
reagent is used in colormetric detection of nitrogen-oxide species.
Whether the source of the nitrogen is biological systems (such as
cell function), or in chemical systems (such as high explosives),
the Griess reagent reacts with nitrogen oxides to produce a highly
colored azo-dye which is used a simple indicator. Although widely
used in many commercial and research applications, the Griess
reagent has only limited storage lifetime, typically 1 to 4 months,
due to decomposition which produce colored impurities, rendering it
unusable for detection.
[0044] The embodiment of the present invention 400 provides a
system wherein the Griess reagent is connected to a vacuum in
preparation. The present invention provides a system to treat the
Griess reagent to improve storage lifetimes at room temperature or
higher to over a year or more. The present invention greatly
extends the useful lifetime of preparations of the Griess reagent
as well as broadens the applications to field testing equipment.
The present invention provides a method comprising the steps of
stabilizing a Griess reagent. In one embodiment the method of
stabilizing a Griess reagent comprises stabilizing a Griess reagent
by removing ambient atmosphere. In one embodiment the method of
stabilizing a Griess reagent comprises removing ambient atmosphere
with a vacuum. In one embodiment the method of stabilizing a Griess
reagent comprises removing ambient atmosphere with an inert
gas.
[0045] The present invention has use in connection with a stand
alone rapid test for explosives used by field and laboratory
personnel to determine the presence and types of explosives. The
present invention is expected to have use to the US Military, EPA,
Law enforcement, and other civilian agencies needing explosives
identification and forensic analysis. The present invention is
expected to have use to companies that sell Griess reagent kits for
biochemical applications.
[0046] While the invention may be susceptible to various
modifications and alternative forms, specific embodiments have been
shown by way of example in the drawings and have been described in
detail herein. However, it should be understood that the invention
is not intended to be limited to the particular forms disclosed.
Rather, the invention is to cover all modifications, equivalents,
and alternatives falling within the spirit and scope of the
invention as defined by the following appended claims.
* * * * *